Need opinions!

My bf n i broke up for about a month n he had sex w another woman....I had to brag that out of him to tell me...and then he went n got a std test done n told me which made me curious....he just told me an hour ago that she called n told him she had chlamydia so that's y he went n got tested but he took the pill before he went to go get tested....my doctor called me n told me I need to come back in bc the test was positive for something. Well we had a conversation wen he told me he was going to get tested that if something g were to come up we wud take care of it n stay together....I'm breaking up w him bc he didn't tell me about her telling him that until an hour ago n he was there at the doctors w me.

Question is should I stay or leave?